In order to save weight, fiber-reinforced plastic materials are increasingly used in modern aircraft construction. Plastic materials used include predominantly duroplastic plastics, for example epoxy resins, which in many cases are reinforced with carbon fibers and comprise an extraordinarily favourable ratio of weight to mechanical strength. Processing the fiber-reinforced duroplastic plastics is often involved and expensive because large-format heatable moulds or autoclaves with vacuum bags are required in order to be able to cure components with the application of pressure and/or temperature to form finished components that are true to shape. Furthermore, the introduction of the reinforcement fibers, in particular their alignment so that it takes into account the flow of force, prior to the impregnation process causes additional difficulties. Moreover, the production of large numbers of carbon-fiber-reinforced duroplastic components while at the same time ensuring good and reliable reproducibility of the geometric and mechanical specifications can be achieved only at significant expense. In recent times fiber-reinforced thermoplastic materials have promised a remedy to the aforesaid, which fiber-reinforced thermoplastic materials can be manufactured with justifiable expenditure in large numbers with constantly good dimensional accuracy, albeit with slightly inferior mechanical properties.
For example, in a primary structure of a mid-sized passenger aircraft up to 15,000 connecting angles are installed in order to interconnect the frame elements and the fuselage cell skin. These connecting angles, or other composite components, can, for example, be manufactured by means of the so-called thermoplastic “stamp forming method”. In this process a blank is cut out of a carbon-fiber-reinforced semifinished product, is heated to above the melting temperature of the thermoplastic plastic, and by means of a likewise heated moulding tool is formed so that it becomes the component with the required component geometry.
During the forming process, for example during right-angle edging of a plate-shaped thermoplastic semifinished product with several reinforcement fiber layers positioned one above the other, due to the so-called “telephone directory effect” and consequently locally different bending radii, bevel formation results in the region of the component edges; in other words, due to interlaminar gliding, inclined edge surfaces form. In a subsequent method-related step, the very sharp-edged edge surfaces, which thus result in the lower region as a result of the material being thin in that location, and as a result of further material, which is excess in the edge region, are separated from the formed component. At the same time the component is given the specified desired dimensions.
Separation can, for example, take place by means of mechanical milling, sawing or water jet cutting. In the region of the component edges reworked in this manner, which component edges now extend perpendicularly to the top or bottom of the component, the reinforcement fibers, which are preferably carbon fibers, as a rule exit perpendicularly so that when these CAP components are connected to metal components, in particular aluminium alloy components, contact corrosion can occur. In order to prevent in particular the occurrence of contact corrosion phenomena, and in order to prevent any associated structural weakening, the reworked component edges generally speaking need to be sealed with an edge seal, for example in the form of a two-component paint or varnish. Application of the paint or varnish can, for example, take place manually by means of a brush.
From DE 89 15 724 U1 for example the creation of a cast edge on a lightweight plate with a honeycomb core structure is known. However, the cast edge is formed subsequently with the use of a castable plastic material.